Domestic dishwasher drying arrangement

ABSTRACT

A FRONT LOADING DISHWASHER DRYING ARANGEMENT IN WHICH AIR DURING THE DRYING CYCLE IS ADMITTED INTO THE DISHWASHER CHAMBER ADJACENT THE LOWER END OF THE FRONT WALL AND EXITS CARRYING MOISTURE THROUGH AN OPENING IN THE UPPER PORTION OF THE REAR WALL, THIS REAR WALL OPENING BEING IN COMMUNICATION WITH A PLENUM FORMED BETWEEN THE TOP WALL OF THE DISHWASHER CHAMBER AND AN OVERLYING CAP STRUCTURE. THE RELATIVELY COOL CAP STRUCTURE SERVES AS A CONDENSER UPON WHICH THE MOSITURE IN THE AIR CONDENSES, AND FROM WHICH IT IS SUBSEQUENTLY EVAPORATED AND ESCAPE FROM THE PLENUM.

Nov. 2, 1971 c. F. TER BUSH 3,616,810

DOMESTIC DISHWASHER DRYING ARRANGEMENT Filed Sept. 24, 1969 2 Sheets-Sheet 1 24 FIG. 1

WITNESSES INVENTOR M 9. W CHARLES F. TER BUSH BY 1 1 (W (1 2m ATTORNEY NW. 1971 c. F. TER BUSH DOMESTIC DISHWASHER DRYING ARRANGEMENT riled Sept. 24. 1969 2 Sheets-Sheet B United States Patent O 3,616,810 DOMESTIC DISHWASHER DRYING ARRANGEMENT Charles F. Ter Bush, Elmhurst, Ill., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa. Filed Sept. 24, 1969, Ser. No. 860,570 Int. Cl. A47l /48 US. Cl. 134-94 7 Claims ABSTRACT OF THE DISCLOSURE A front loading dishwasher drying arrangement in which air during the drying cycle is admitted into the dishwasher chamber adjacent the lower end of the front wall and exits carrying moisture through an opening in the upper portion of the rear wall, this rear wall opening being in communication with a plenum formed between the top wall of the dishwasher chamber and an overlying cap structure. The relatively cool cap structure serves as a condenser upon which the moisture in the air condenses, and from which it is subsequently evaporated and escapes from the plenum.

BACKGROUND OF THE INVENTION Field of the invention The invention pertains to the art of drying arrangements for domestic dishwashers.

Description of the prior art In the drying cycle of typical dishwashers the air in the tub is heated and vented out of the tub or washing chamber. To get the warm moist air out of the dishwasher tub, one common arrangement has been to admit air into the tub either at the bottom front or at the rear of the machine, and to provide an exit opening for the warm moist air out at the top front area of the door. With under counter dishwashers it has been considered to be inadvisable to deliver large quantities of warm moist air out the rear or sides because of the possibility of damage to the overlying kitchen counter top. When the warm moist air exits out the front into the room it is typically visible and also strikes the cooler trim sections located in this area with the possibility of moisture condensing thereon and running down the door face. It will be appreciated that it would be considered better practice to not have the visible moisture entering the room, and to also avoid the problem of condensation on the visible exterior surfaces of the dishwashing machine. Examples of efforts to avoid this may be found in U.S. Pats. 2,390,757 and 3,387,382, which deal with arrangements in which an attempt is made to condense the moisture either in the tub, in the first instance, or exteriorly of the tub in the second instance. However in the second noted patent most of the moisture which does condense exteriorly of the tub returns to the tub.

SUMMARY OF THE INVENTION In accordance with my invention it is proposed that the moisture laden air exit through an opening in the rear wall of the washing chamber and near the top, and be directed into a plenum formed above the top wall of the tub by providing a cap-shaped structure overlying the top wall of the tub. The inlet to the washing chamber or tub is through an opening in the lower portion of the front wall of the washing chamber, the front wall typically being formed by a swing-down door. The moisture laden air which enters the plenum overlying the tub tends to condense on the inner face of the cap which is relatively cool as compared to the top wall of the tub. This moisture is subsequently gradually dissipated by natural convection Patented Nov. 2, 1971 "ice DRAWING DESCRIPTION FIG. 1 is a partly broken side view, schematically represented in part, of a dishwasher incorporating my invention;

FIG. 2 is a vertical sectional view corresponding to one taken along the line II-II of FIG. 3;

FIG. 3 is a vertical sectional view corresponding to one taken along the line IIIIII of FIG. 1;

FIG. 4 is a partly broken and exploded perspective view of the top portion of the tub and the cap before the cap is installed; and

FIG. 5 is a fragmentary sectional view illustrating the relationship between the front edge of the lower wall of the tub and the lower edge of the inner panel of the door which together define the opening through which air is admitted into the tub during a drying cycle.

DESCRIPTION OF THE PREFERRED EMBODIMENT The generally box-shaped washing chamber or tub of the dishwasher shown in FIG. 1 is formed by top wall 10, bottom wall 12, rear wall 14, opposite side walls 16, and a front, swing-down door 18 which covers the front access opening 20 through which dishes are inserted and removed. The dishwasher is typically installed below a counter top 22.

The interior of the tub is arranged to receive the conventional slide out dish racks (not shown), and water for the washing and rinsing operations is supplied through line 24 having a solenoid valve 26 or other control means therein for controlling the flow of water to the inlet fitting 28 which is in communication with the interior of the tub. A resistance heating element 30 of conventional form is provided in the lower part of the tub and is energized at least during a drying cycle to provide heat to facilitate drying. Conventional control means are provided in the upper part 32 of the door and controls the washing cycle, rinsing cycle, and drying cycle in conventional fashion.

In accordance with the currently preferred embodiment of the invention, the upper portion of the rear wall 14 is provided with a tub outlet vent arrangement generally designated 34. An overlying cap 36 is mounted on the top of the tub so that a plenum 38 is formed between the top wall 10 and the cap. The plenum 38 is in communication with the tub outlet vent arrangement 34 so that moisture laden air exiting from the vent 34 passes upwardly into the plenum during the drying cycle. The admission of air into the tub during the drying cycle is by way of a gap 40 at the lower edge of the door in the currently preferred embodiment. The flow of air into the tub and out of it to the plenum is indicated by the directional arrows in FIG. 1.

The tub may be of conventional material such as steel, while the cap may be conveniently made of polyethylene material which is vacuum formed, for example, to the particular shape shown in FIG. 4. As such, it has the general shape of a shallow, inverted pan. The front edge 42 of the cap is dimensioned to fit relatively closely to the facing portion of the tub top wall 10 and is taped thereto so that effectively a seal between the tub exterior and the front edge of the cap is formed to prevent the escape of moisture therealong. The depending side walls 44 are spaced apart sufiiciently to at least accommodate a strip of porous material 46, which may be open cell urethane foam for example, between the inner face of the cap side walls and the outer faces of the tub wall 16. These strips are characterized as drip guards and serve to trap moisture droplets which condense on the side walls 44 and tend to run down. The depending rear wall 48 of the cap may be designed to conform more closely to the facing portion of the tub rear wall 14 adjacent the vent opening and also carries a drip guard 46. The air admitted to the plenum 38 exits therefrom through the gaps along the sides and rear after being relieved of most of the moisture through condensation on the inner surfaces of the cap.

The currently preferred arrangement for the tub outlet vent 34 is best illustrated in FIG. 2. The upper portion of the rear wall 14 of the tub is displaced or embossed outwardly to form a rectangular-shaped, outwardly-offset portion 50. Adjacent the upper edge of the offset portion, the pan is cut and the upper margin is flanged inwardly as at 52 so that the opening through which the moisture laden air can exit is formed below the lower edge of the flange 52 and the upper edge of the pan wall 50. A strip of open-cell foam extends across the gap between flange 52 and the upper edge pan wall 50, as shown, to dampen any explosion elfect which sometimes occurs when the machine is restarted after a door opening during a washing or rinsing operation. A generally rectangular cover 54 (also see FIG. 3) is fastened to the rear wall 14 of the tub to overlie the major portion of the offset area. The cover 54 may also be vacuum formed plastic and provided with some stifl'ening ribs as at 56. It also includes a forwardly offset upper margin 58 which is spaced forwardly from the flange 52 and upper part of the rear wall 14 of the tub.

The main purpose of the cover 54 is to insure that during the washing and rinsing operations that water is not thrown out through the tub outlet vent. During a drying cycle most of the moisture laden air will leave the tub through the opening 60 defined between the wall 50 and the lower edge of the cover 58, although a portion may find its way to the outlet through the opening 62 defined between the upper cover portion and wall therebehind. Also, during any explosion condition in the tub (which occurs after the door has been opened during a washing or rinsing cycle and then closed and the machine restored to operation), any water which tends to be carried out of the vent through the upper opening 62 is deflected back toward the tub by the flange 52.

As noted before, it is preferred that the air admission opening in the front wall of the dishwasher be formed by providing a gap along the lower edge of the door 18. In the current tub configuration, in which the lower wall 12 (FIG. includes an up-turned front flange 64, the gap 40 may be provided between the lower edge of the inner panel 18a of the hollow door 18, and the underlying wall 12 of the tub. This gap extends for most of the width of the tub by simply terminating the sealing gasket (not shown) which outlines the front opening 20, several inches in from the side walls 16. The depth of water in the sump of the tub may be controlled in connection with the configuration of the lower wall of the tub so that the level of water is either above or below the lower edge of the inner panel 18. A preferred arrangement is to control the level of water so that the gap is covered by the normal amount of water in the tub during a washing and rinsing operation since this will serve as a trap against the emission of the sounds of washing from the dishwasher as well as the flow of any air, the gap being the only opening at the front of the machine to the tub.

In summary as to the operation of the disclosed embodiment during the drying cycle, the control 32 energizes the heater 30. The heated air rises and exits with a heavy load of moisture therein through the tub outlet vent 34 in the rear of the tub. Additional air is drawn into the tub through the inlet 40. The moisture in the air passing into the plenum 38 formed below the cap 36 tends to condense on the inner surfaces of the cap and remains there until it gradually dissipates by natural convection into the area under the counter top and into the room. Since the moisture only dissipates into the room at a relatively slow rate after the drying cycle is completed, the concentration of moisture present under the counter top at any given time will not be sufficient to cause any counter top damage under normal conditions. During the drying cycle, the warm air in the plenum 38 is relieved of most of its moisture content by condensation upon the cap, and is dissipated into the area under the counter top through the gaps along the side and rear depending walls of the cap. The drip guard strips trap moisture droplets which would tend to run down the side walls of the condenser, to the extent that such moisture drops accumulate.

It will be appreciated that the preferred embodiment includes the tub outlet vent arrangement in the rear wall and with the inlet at the lower portion of the front wall so that the convection promoted by the heater 30 aids the movement of the air in a natural course. It would of course be within the scope of the invention to provide the vent means in the top wall or on one or both of the side walls.

I claim:

1. In a domestic dishwasher:

means defining a washing chamber including a front wall, a top wall, a rear wall, opposite side walls, and a bottom wall;

means for operating said dishwasher in a washing, rinsing, and drying operation;

heating means in the lower portion of said chamber for supplying heat to said chamber during a drying operation;

means in the lower portion of said front wall defining an opening for admitting air into said chamber during said drying operation; means in the upper portion of said chamber defining an opening for exhausting moisture laden air during said drying operation; and a a cap in spaced relation and overlying a major portion of said top wall to define a plenum between said cap and top wall, said plenum being in communication with said exhaust opening to receive moisture laden air during said drying operation and effect the condensation of a major portion of said moisture upon the inner face of said cap, said cap being in generally sealed relation with said washing chamber along the front thereof, and being generally imperforate throughout its horizontal extent, to prevent the exit of air from said plenum in both the forward and the upward directions.

2. In a dishwasher according to claim 1:

said exhaust opening is defined in the upper portion of at least one of said vertical walls other than said front wall.

3. In a dishwasher according to claim 2 wherein:

said exhaust opening is located in the upper portion of said rear wall.

4. In a dishwasher according to claim 1 wherein:

said cap overlies substantially the entire top wall and includes depending opposite side walls and a rear wall spaced apart from the respective opposite side walls and rear wall of said tub to define gaps therebetween through which air admitted to said cap may exit.

5. In a dishwasher according to claim 4 including:

drip guard means provided on the inner face of said cap depending walls for trapping moisture running down along said inner surfaces of said cap walls.

6. In a dishwasher according to claim 1;

cover means in facing relation to said exhaust opening but spaced apart therefrom, to shield said exhaust opening from water spray generated during washing and rinsing operations.

7. A dishwasher comprising:

means defining a washing chamber including a front wall, a rear wall, and a top wall;

means for supplying water to said chamber for a washing and a rinsing operation;

heating means in the lower portion of said chamber for 6 supplying heat to said chamber during a drying op- References Cited eration; means in the lower portion of said front wall defining UNITED STA:TES PATENTS an opening for admitting air into said washing cham- 856,478 6/1907 Lewls 3473 UX ber during said drying operation; 5 1,570,552 1/1926 Bqwerbank means in the upper portion of said rear wall defining 2,301,601 11/1942 Wlttwer et a1 134 200' X an opening for exhausting moisture laden air during 2,790,451 4/1957 P P 134 20O X said drying operation; and 3,356,431 12/1967 Martlmak 34231 X cap means in spaced relation and overlying a major portion of said top wall to define a plenum between 1 DANIEL BLUM Primary 'Exammer said cap and top wall, said plenum being in communi- U S Cl X R cation with said rear wall opening to receive moisture laden air during said drying operation so that con- 34-73, 231; 134-107, 182 densation of said moisture will occur on the inner face of said cap means. 15 

